1. Field of the Invention
The present invention relates to a mold-in fastening member (hereinafter may be referred to as xe2x80x9cfastening memberxe2x80x9d) to be embedded in the surface of a molded resin article such as automotive seat cushions and office chair cushions. The fastening member embedded in the cushion is useful to manufacture automotive seats or office chairs by fixing an upholstery material such as cloth to the cushion.
2. Description of Prior Arts
An automotive seat or office chair seat is generally produced by covering the surface of a cushion made of foamed polyurethane or the like with a seat cover (upholstery material). In the conventional production, a so-called Hogring method has been employed, in which a cushion having molded-in wires is produced by embedding wires retained in a recess of a mold into the cushion, and the seat cover is attached to the cushion by means of a large number of metal fixing members which engage the molded-in wires with the seat cover. The procedure of the Hogring method is accomplished by the aid of an electric tool.
A new molding method has recently been proposed for the production of an automotive seat. This method involves the steps of placing fastening members each having a large number of engaging elements on its top surface and a large number of anchoring elements on its back surface, i.e., flat fastener tapes, in the predetermined positions of a mold; injecting a foaming resin into the mold; and expanding the resin such that a portion of the fastener tapes are integrally embedded in the surface of the cushion and the engaging elements are bared on its outer surface (so-called mold-in method). The cushion is finally covered with a seat cover having elements capable of engaging with the engaging elements of the fastener tape.
The above mold-in method needs, during the molding process while maintaining the fastening member retained on the recess of the mold, to prevent the foaming resin (hereinafter may be referred to as xe2x80x9cfoaming resin compositionxe2x80x9d) from entering into the top side of the fastening tape having the engaging elements through the gap between the fastener tape and the mold recess, since this can cause a problem of burying the engaging elements in the foamed resin.
A conventional method for solving this problem is shown in FIG. 4. The fastening member (A) is made up of a flat fastener tape (E), a steel strip (F) and a cover film (G). The flat fastener tape (E) has a large number of engaging elements (C) and anchoring elements (D) respectively formed on the top and back surfaces of its substrate (B). The steel strip (F) disposed on the engaging elements (C) is magnetically attached to a magnet (J) embedded in the bottom of the mold during the mold-in process. The cover film (G) entirely covers the steel strip (F) and the engaging elements (C) to prevent the foaming resin composition from entering into the side of the fastening member having the engaging elements (C). The periphery of the cover film (G) is integrally bonded to the periphery of the flat fastener tape (E) by adhesives or heat sealing.
The fastening member (A) is fixed in the recess (K) of the mold by the magnetic force exerted on the steel strip (F) by the magnet (J) arranged at the bottom of the recess (K). Subsequently, a foaming resin composition is injected into the mold so as to produce a cushion in which the anchoring elements (D) are embedded. After taking the molded cushion out of the mold, the cover film (G) and the steel strip (F) are removed from the cushion, so that the engaging elements (C) of the flat fastener are bared on the surface of the cushion.
Another fastening member of the mold-in type is disclosed in Japanese Patent Application Laid-Open No. 64-9708/1989. The proposed fastening member is a flat fastener having a groove along its entire periphery. In a bottom portion of a mold, a recess for receiving the flat fastener is provided, around which a ridge or groove is further formed. The flat fastener is fixed to the mold by fitting the fastener groove with the ridge or groove of the mold. It is reported that, the engaging elements of the fastening member are sealed against a foaming resin by the groove formed on the periphery of the flat fastener and the ridge or groove around the recess for receiving the flat fastener.
Still another fastening member of mold-in type is disclosed in Japanese Utility Model Application Laid-Open No. 3-58109/1991. The fastening member is a flat fastener tape having on its entire outer periphery a fitting member having a rectangular section. The fastening member is undesirably large in size due to the additional fitting member. In addition, the fastening member has another disadvantage that the fitting member has to be formed separately from the flat fastener tape and then attached to the periphery of the flat fastener tape. This disadvantage leads to low productivity due to complicated operations therefor.
Further, French Patent Application Laid-Open No. 2423666 discloses a fastening member capable of being fitted to a recessed portion by bending the fastening member in the width direction.
Also, Japanese Patent Application Laid-Open No. 6-99443/1994 discloses a fastening member which prevents a molding resin from reaching the surface of the fastening member having the engaging elements, by press-fitting the periphery of the fastening member against a shoulder of the recessed groove formed on a mold. In an embodied method of press-fitting, this prior art discloses to press-fit the peripheral portion of the flat fastener to the shoulder of the recessed groove of the mold by magnetically attracting an iron powdercontaining layer formed on an entire part or only a peripheral portion of the engaging surface of the fastening member toward magnets disposed on the shoulder of the recessed groove of the mold.
The above Hogring method of attaching the seat cover to the cushion has the disadvantage of requiring a large number of metal fixing members and a great deal of labor. In addition, it poses a problem with safety and health, e.g., due to possible wounds and tenosynovitis which results from using an electric tool for the metal fixing members. Another disadvantage is that the cushion after scrapping cannot be easily recycled because it contains metal parts such as wires and fixing members.
The mold-in fastening member shown in FIG. 4 has the disadvantage that it is necessary to remove the steel strip (F) and the cover film (G) after molding. After removal, they should be disposed as waste. Another disadvantage is that the film (G) has to be completely removed with great care, because even a small piece of film remaining on the engaging elements reduces the engaging force and deteriorates the appearance. The removal of the film is troublesome and the removal of the steel strip (F) may injure the fingers.
The fastening member disclosed in Japanese Patent Application Laid-Open No. 64-9708/1989 has the disadvantage of requiring a complicated structure in both the flat fastener tape and the mold, making the production method complicated. The former has the groove on its periphery, and the latter is provided with a ridge or a groove along the periphery of the recess for receiving the flat fastener tape. In addition, since the fastener has a periphery having no engaging elements, the width of the fastener is inevitably increased. This is undesirable especially in the case of narrow fasteners because the numbers of engaging elements and anchoring elements are correspondingly decreased, thereby reducing the bonding force of the fastening member to the molded article or engaging force with the upholstery material.
The fastening member disclosed in French Patent Application Laid-Open No. 2423666 is superior in sealing between the recess of the mold and the fastening member once the fastening member is completely fitted to the recess of the mold. However, delicate and careful work is required to fit the fastening member to the recess of the mold, resulting in impractically low working efficiency. In addition, when the molded article with the molded-in fastening member is removed from the mold, the fastening member, if too strongly fitted to the recess of the mold, tends to be separated from the molded resin body. This problem is difficult to solve.
In the method disclosed in Japanese Patent Application Laid-Open No. 6-99443/1994, the recess of the mold can be effectively sealed against access of the molding resin only when the periphery of the fastening member and the shoulder around the recess of the mold are flat, because both can be closely contacted with each other. However, it is very difficult in industrial process to form the iron powder-containing layer having uniformly flat surface along the entire periphery of the fastening member of several tens centimeter long. Therefore, it is substantially impossible to attain a sealing sufficient for the practical use.
In view of the above problems, an object of the present invention is to provide a mold-in fastening member which is kept fixed to the shoulder of the recess formed on a mold during the molding process to thereby completely prevent a foaming resin composition from entering into the side of fastening member having engaging elements. Another object of the present invention is to provide a mold-in fastening member having a small size as well as excellent productivity, safety and working efficiency. Still another object of the present invention is to provide a process for the production of a resin-molded article having the molded-in fastening member on the surface thereof.
Namely, the present invention provides a mold-in fastening member that can be molded into a resin article, comprising (a) a substrate having a front surface and a back surface; (b) a plurality of engaging elements provided on the front surface; (c) a plurality of anchoring elements provided on the back surface, the anchoring elements being embedded into the resin article to fix the mold-in fastening member thereto; (d) a ferrite-containing layer formed on the front surface; (e) marginal portions continuously extending along respective lengthwise edges of the substrate; and (f) grooves formed on the substrate, which extend along the respective marginal portions to render the marginal portions easily bending relative to the substrate. In a preferred embodiment of the mold-in fastening member, the ferrite-containing layer is provided on the front surface within the area of the engaging elements, and not provided on the marginal portions.
The present invention also provides a process for producing a molded resin article having a fastening member, comprising the steps of (a) fitting the fastening member mentioned above to a recess formed on a mold so that the engaging elements are received in the recess and the marginal portions are placed on a shoulder of the recess to keep the grooves inside the shoulder; (b) sealing the front surface in the recess by press-contacting the marginal portions with the shoulder by a magnetic attracting force between the ferrite-containing layer and a magnet disposed at the bottom of the recess; (c) injecting a foaming resin into the mold; and (d) curing the foaming resin, thereby embedding the anchoring elements into the cured foaming resin. In a preferred embodiment of the process, the ferrite-containing layer is provided on the front surface within the area of the engaging elements, and not provided on the marginal portions.